Your radius is one of the bones in your forearm. It helps you move your arm and wrist. When you injure your radius, it’s likely the muscles and nerves attached to it will be damaged, too.


The radius is a bone in your forearm that helps you move your arm and wrist.
A radius bone anatomy labeled.

What is the radius?

The radius is one of the bones in your forearm. It helps you move your arm and wrist. Your radius also supports lots of important muscles, tendons, ligaments and blood vessels.

If you experience a fractured (broken) radius, you might need surgery to repair your bone and physical therapy to help you regain your strength and ability to move.

Your radius — like all bones — can be affected by osteoporosis.

Because your radius is connected to so many muscles and nerves, injuries to one often can affect the others.


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What does the radius do?

Your radius has several important jobs, including:

  • Helping your forearm and wrist move, flex and rotate.
  • Holding seven muscles in place.
  • Stabilizing the rest of your arm, wrist and hand.


Where is the radius located?

Your radius is one of two bones in your forearm. The other is your ulna. The radius is opposite your ulna, on the lateral (thumb) side of your forearm. Your radius rotates over your ulna when you stretch your arm straight out in front of you with your palms facing down. They’re more parallel to each other when you hold your arms straight out with your palms face up.


What does the radius look like?

Your radius has a small end where it meets your humerus (upper arm bone), a long shaft in the middle that’s slightly curved and a wider end that meets your wrist. It’s thicker and slightly shorter than your ulna.

Even though it’s one long bone, your radius is made up of several parts. These include:

Radius proximal aspect

The upper (proximal) end of your radius connects to your humerus. The proximal end (aspect) contains the:

  • Head.
  • Neck.
  • Radial tuberosity.

Radius shaft

The shaft is the long middle portion of the radius that supports the weight of your forearm and gives it its shape.

Radius distal aspect

The lower (distal) end of your radius forms the top of your wrist joint. It’s wider than the rest of your radius where it meets your scaphoid and lunate (wrist or carpal bones). The distal end of the radius includes:

  • Styloid process.
  • Ulnar notch.

All these parts and labels are usually more for your healthcare provider to use as they describe where you’re having pain or issues. If you ever break your radius — a radial fracture — your provider might use some of these terms to describe where your bone was damaged.

How big is the radius?

Your radius is the third longest bone in your arm and is one of the longest bones in your body. Most adults’ radius bones are around 10 inches long.


Conditions and Disorders

What are the common conditions and disorders that affect the radius?

The most common issues that affect the radius are fractures, osteoporosis and damage to nerves or muscles around it.

Radius fractures

A bone fracture is the medical term for a broken bone. The most common causes of radius fractures include:

Symptoms of a fracture include:

  • Pain.
  • Swelling.
  • Tenderness.
  • Inability to move your arm like you usually can.
  • Bruising or discoloration.
  • A deformity or bump that’s not usually on your body.

Some fractures that affect the radius include:

Go to the emergency room right away if you’ve experienced a trauma or think you have a fracture.


Osteoporosis weakens bones, making them more susceptible to sudden and unexpected fractures. It usually doesn’t cause any symptoms you can notice, so many people don’t know they have osteoporosis until after it causes them to break a bone.

Women and people assigned female at birth and adults older than 65 have an increased risk for developing osteoporosis. Talk to your provider about a bone density test that can catch osteoporosis before it causes a fracture.

Nursemaid elbow

Nursemaid elbow is a common injury for young children. You might also see it referred to as a “pulled elbow.” It’s a partially dislocated radius where it meets a child’s elbow. It happens because kids’ ligaments are looser than adults’. Pulling on your child’s arm or hand causes nursemaid elbow. It usually happens accidentally after motions like tugging your child’s arm so they don’t walk into the street, or playfully lifting them up by their hands.

What tests are done on the radius?

The most common test done to check the health of your radius is a bone density test. It’s sometimes called a DEXA or DXA scan. A bone density test uses low levels of X-rays to measure how strong your bones are. It’s a way for your provider to track bone loss as you age.

If you’ve experienced a humeral fracture, your provider or surgeon might need imaging tests, including:

What are common treatments done to the radius?

Your radius won’t need treatment unless you’ve experienced a fracture or injury or have osteoporosis.

Radius fracture treatment

How your fracture is treated depends on which type it is and what caused it. You’ll need some form of immobilization like a splint or cast. You might need surgery to realign (set) your bone to its correct position so it can heal.

Osteoporosis treatment

Treatments for osteoporosis can include exercise, vitamin and mineral supplements and medications.

Your provider will help you develop a treatment plan that’s customized for you and your bone health.


Keeping your radius healthy

Following a good diet and exercise plan and seeing your healthcare provider for regular checkups will help you maintain your bone (and overall) health. If you’re older than 50 or have a family history of osteoporosis, talk to your provider about a bone density scan.

Follow these general safety tips to reduce your risk of an injury:

  • Always wear your seatbelt.
  • Wear the right protective equipment for all activities and sports.
  • Make sure your home and workspace are free from clutter that could trip you or others.
  • Always use the proper tools or equipment at home to reach things. Never stand on chairs, tables or countertops.
  • Follow a diet and exercise plan that’ll help you maintain good bone health.
  • Use your cane or walker if you have difficulty walking or have an increased risk of falls.

Additional Common Questions

What’s the difference between the radius and ulna?

Your radius and ulna are the two bones that make up your forearm. They share the functions that let your arm and wrist move.

Your ulna is slightly longer than your radius. It’s on the medial (pinky) side of your forearm.

The similarities between your radius and ulna might be confusing, and it’s easier to think of them as equally important pieces of your arm. They work together to support your forearm and wrist. Their shape and how they link together lets your wrist and hand rotate smoothly.

A note from Cleveland Clinic

Your radius is an important bone that lets your arm and wrist move. Most people never think about their radius until something is wrong with it. Talk to your provider about your osteoporosis risk to catch any issues with your bones before they cause a fracture. Anything you do to improve your overall health will also help keep your bones strong.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 12/09/2022.

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